2. Basic morphology evolution
• 2 processes are occurring
• Dissolution of silver atoms
• Diffusion of gold atoms
• Gold atoms begin to pack together,
leaving layers of more silver atoms
behind
• When silver is almost completely
dissolved, gold atoms continue to
diffuse
• https://www.youtube.com/watch?v=
WXGfjA2rmdE
3. • The longer the alloy is in the nitric acid, the
larger the pores get due to diffusion
• It was found that the diffusion was happening
to fast for room temperature
• Why?
• The nitric acid causes faster diffusion on the
surface
• Anions in the solution weaken the binding strength
of gold atoms on the surface
Diffusion after Silver is removed
300 nm
300 nm
10 min in Nitric Acid
30 min in Nitric Acid